Commit 9bfc445e authored by David S. Miller's avatar David S. Miller

Merge branch 'doc-net-ieee802154-move-from-plain-text-to-rst'

Stefan Schmidt says:

====================
doc: net: ieee802154: move from plain text to rst

The ieee802154 subsystem doc was still in plain text. With the networking book
taking shape I thought it was time to do the first step and move it over to rst.
This really is only the minimal conversion. I need to take some time to update
and extend the docs.

The patches are based on net-next, but they only touch the networking book so I
would not expect and trouble. From what I have seen they would go through
Jonathan's tree after being acked by Dave? If you want this patches against a
different tree let me know.
====================
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents eeaadd82 8a42eda2
===============================
Linux IEEE 802.15.4 implementation IEEE 802.15.4 Developer's Guide
===============================
Introduction Introduction
============ ============
The IEEE 802.15.4 working group focuses on standardization of the bottom The IEEE 802.15.4 working group focuses on standardization of the bottom
two layers: Medium Access Control (MAC) and Physical access (PHY). And there two layers: Medium Access Control (MAC) and Physical access (PHY). And there
are mainly two options available for upper layers: are mainly two options available for upper layers:
- ZigBee - proprietary protocol from the ZigBee Alliance
- 6LoWPAN - IPv6 networking over low rate personal area networks - ZigBee - proprietary protocol from the ZigBee Alliance
- 6LoWPAN - IPv6 networking over low rate personal area networks
The goal of the Linux-wpan is to provide a complete implementation The goal of the Linux-wpan is to provide a complete implementation
of the IEEE 802.15.4 and 6LoWPAN protocols. IEEE 802.15.4 is a stack of the IEEE 802.15.4 and 6LoWPAN protocols. IEEE 802.15.4 is a stack
of protocols for organizing Low-Rate Wireless Personal Area Networks. of protocols for organizing Low-Rate Wireless Personal Area Networks.
The stack is composed of three main parts: The stack is composed of three main parts:
- IEEE 802.15.4 layer; We have chosen to use plain Berkeley socket API,
the generic Linux networking stack to transfer IEEE 802.15.4 data
messages and a special protocol over netlink for configuration/management
- MAC - provides access to shared channel and reliable data delivery
- PHY - represents device drivers
- IEEE 802.15.4 layer; We have chosen to use plain Berkeley socket API,
the generic Linux networking stack to transfer IEEE 802.15.4 data
messages and a special protocol over netlink for configuration/management
- MAC - provides access to shared channel and reliable data delivery
- PHY - represents device drivers
Socket API Socket API
========== ==========
int sd = socket(PF_IEEE802154, SOCK_DGRAM, 0); .. c:function:: int sd = socket(PF_IEEE802154, SOCK_DGRAM, 0);
.....
The address family, socket addresses etc. are defined in the The address family, socket addresses etc. are defined in the
include/net/af_ieee802154.h header or in the special header include/net/af_ieee802154.h header or in the special header
in the userspace package (see either http://wpan.cakelab.org/ or the in the userspace package (see either http://wpan.cakelab.org/ or the
git tree at https://github.com/linux-wpan/wpan-tools). git tree at https://github.com/linux-wpan/wpan-tools).
6LoWPAN Linux implementation
============================
The IEEE 802.15.4 standard specifies an MTU of 127 bytes, yielding about 80
octets of actual MAC payload once security is turned on, on a wireless link
with a link throughput of 250 kbps or less. The 6LoWPAN adaptation format
[RFC4944] was specified to carry IPv6 datagrams over such constrained links,
taking into account limited bandwidth, memory, or energy resources that are
expected in applications such as wireless Sensor Networks. [RFC4944] defines
a Mesh Addressing header to support sub-IP forwarding, a Fragmentation header
to support the IPv6 minimum MTU requirement [RFC2460], and stateless header
compression for IPv6 datagrams (LOWPAN_HC1 and LOWPAN_HC2) to reduce the
relatively large IPv6 and UDP headers down to (in the best case) several bytes.
In September 2011 the standard update was published - [RFC6282].
It deprecates HC1 and HC2 compression and defines IPHC encoding format which is
used in this Linux implementation.
All the code related to 6lowpan you may find in files: net/6lowpan/*
and net/ieee802154/6lowpan/*
To setup a 6LoWPAN interface you need:
1. Add IEEE802.15.4 interface and set channel and PAN ID;
2. Add 6lowpan interface by command like:
# ip link add link wpan0 name lowpan0 type lowpan
3. Bring up 'lowpan0' interface
Kernel side Drivers
============= =======
Like with WiFi, there are several types of devices implementing IEEE 802.15.4. Like with WiFi, there are several types of devices implementing IEEE 802.15.4.
1) 'HardMAC'. The MAC layer is implemented in the device itself, the device 1) 'HardMAC'. The MAC layer is implemented in the device itself, the device
exports a management (e.g. MLME) and data API. exports a management (e.g. MLME) and data API.
2) 'SoftMAC' or just radio. These types of devices are just radio transceivers 2) 'SoftMAC' or just radio. These types of devices are just radio transceivers
possibly with some kinds of acceleration like automatic CRC computation and possibly with some kinds of acceleration like automatic CRC computation and
comparation, automagic ACK handling, address matching, etc. comparation, automagic ACK handling, address matching, etc.
Those types of devices require different approach to be hooked into Linux kernel. Those types of devices require different approach to be hooked into Linux kernel.
HardMAC HardMAC
======= -------
See the header include/net/ieee802154_netdev.h. You have to implement Linux See the header include/net/ieee802154_netdev.h. You have to implement Linux
net_device, with .type = ARPHRD_IEEE802154. Data is exchanged with socket family net_device, with .type = ARPHRD_IEEE802154. Data is exchanged with socket family
...@@ -64,9 +89,8 @@ net_device with a pointer to struct ieee802154_mlme_ops instance. The fields ...@@ -64,9 +89,8 @@ net_device with a pointer to struct ieee802154_mlme_ops instance. The fields
assoc_req, assoc_resp, disassoc_req, start_req, and scan_req are optional. assoc_req, assoc_resp, disassoc_req, start_req, and scan_req are optional.
All other fields are required. All other fields are required.
SoftMAC SoftMAC
======= -------
The MAC is the middle layer in the IEEE 802.15.4 Linux stack. This moment it The MAC is the middle layer in the IEEE 802.15.4 Linux stack. This moment it
provides interface for drivers registration and management of slave interfaces. provides interface for drivers registration and management of slave interfaces.
...@@ -79,99 +103,78 @@ This layer is going to be extended soon. ...@@ -79,99 +103,78 @@ This layer is going to be extended soon.
See header include/net/mac802154.h and several drivers in See header include/net/mac802154.h and several drivers in
drivers/net/ieee802154/. drivers/net/ieee802154/.
Fake drivers
------------
In addition there is a driver available which simulates a real device with
SoftMAC (fakelb - IEEE 802.15.4 loopback driver) interface. This option
provides a possibility to test and debug the stack without usage of real hardware.
Device drivers API Device drivers API
================== ==================
The include/net/mac802154.h defines following functions: The include/net/mac802154.h defines following functions:
- struct ieee802154_hw *
ieee802154_alloc_hw(size_t priv_data_len, const struct ieee802154_ops *ops):
allocation of IEEE 802.15.4 compatible hardware device
- void ieee802154_free_hw(struct ieee802154_hw *hw): .. c:function:: struct ieee802154_dev *ieee802154_alloc_device (size_t priv_size, struct ieee802154_ops *ops)
freeing allocated hardware device
- int ieee802154_register_hw(struct ieee802154_hw *hw): Allocation of IEEE 802.15.4 compatible device.
register PHY which is the allocated hardware device, in the system
- void ieee802154_unregister_hw(struct ieee802154_hw *hw): .. c:function:: void ieee802154_free_device(struct ieee802154_dev *dev)
freeing registered PHY
- void ieee802154_rx_irqsafe(struct ieee802154_hw *hw, struct sk_buff *skb, Freeing allocated device.
u8 lqi):
telling 802.15.4 module there is a new received frame in the skb with
the RF Link Quality Indicator (LQI) from the hardware device
- void ieee802154_xmit_complete(struct ieee802154_hw *hw, struct sk_buff *skb, .. c:function:: int ieee802154_register_device(struct ieee802154_dev *dev)
bool ifs_handling):
telling 802.15.4 module the frame in the skb is or going to be Register PHY in the system.
transmitted through the hardware device
.. c:function:: void ieee802154_unregister_device(struct ieee802154_dev *dev)
Freeing registered PHY.
.. c:function:: void ieee802154_rx_irqsafe(struct ieee802154_hw *hw, struct sk_buff *skb, u8 lqi):
Telling 802.15.4 module there is a new received frame in the skb with
the RF Link Quality Indicator (LQI) from the hardware device.
.. c:function:: void ieee802154_xmit_complete(struct ieee802154_hw *hw, struct sk_buff *skb, bool ifs_handling):
Telling 802.15.4 module the frame in the skb is or going to be
transmitted through the hardware device
The device driver must implement the following callbacks in the IEEE 802.15.4 The device driver must implement the following callbacks in the IEEE 802.15.4
operations structure at least: operations structure at least::
struct ieee802154_ops {
...
int (*start)(struct ieee802154_hw *hw);
void (*stop)(struct ieee802154_hw *hw);
...
int (*xmit_async)(struct ieee802154_hw *hw, struct sk_buff *skb);
int (*ed)(struct ieee802154_hw *hw, u8 *level);
int (*set_channel)(struct ieee802154_hw *hw, u8 page, u8 channel);
...
};
- int start(struct ieee802154_hw *hw):
handler that 802.15.4 module calls for the hardware device initialization.
- void stop(struct ieee802154_hw *hw):
handler that 802.15.4 module calls for the hardware device cleanup.
- int xmit_async(struct ieee802154_hw *hw, struct sk_buff *skb):
handler that 802.15.4 module calls for each frame in the skb going to be
transmitted through the hardware device.
- int ed(struct ieee802154_hw *hw, u8 *level):
handler that 802.15.4 module calls for Energy Detection from the hardware
device.
- int set_channel(struct ieee802154_hw *hw, u8 page, u8 channel):
set radio for listening on specific channel of the hardware device.
Moreover IEEE 802.15.4 device operations structure should be filled. struct ieee802154_ops {
...
int (*start)(struct ieee802154_hw *hw);
void (*stop)(struct ieee802154_hw *hw);
...
int (*xmit_async)(struct ieee802154_hw *hw, struct sk_buff *skb);
int (*ed)(struct ieee802154_hw *hw, u8 *level);
int (*set_channel)(struct ieee802154_hw *hw, u8 page, u8 channel);
...
};
Fake drivers .. c:function:: int start(struct ieee802154_hw *hw):
============
In addition there is a driver available which simulates a real device with Handler that 802.15.4 module calls for the hardware device initialization.
SoftMAC (fakelb - IEEE 802.15.4 loopback driver) interface. This option
provides a possibility to test and debug the stack without usage of real hardware.
See sources in drivers/net/ieee802154 folder for more details. .. c:function:: void stop(struct ieee802154_hw *hw):
Handler that 802.15.4 module calls for the hardware device cleanup.
6LoWPAN Linux implementation .. c:function:: int xmit_async(struct ieee802154_hw *hw, struct sk_buff *skb):
============================
The IEEE 802.15.4 standard specifies an MTU of 127 bytes, yielding about 80 Handler that 802.15.4 module calls for each frame in the skb going to be
octets of actual MAC payload once security is turned on, on a wireless link transmitted through the hardware device.
with a link throughput of 250 kbps or less. The 6LoWPAN adaptation format
[RFC4944] was specified to carry IPv6 datagrams over such constrained links,
taking into account limited bandwidth, memory, or energy resources that are
expected in applications such as wireless Sensor Networks. [RFC4944] defines
a Mesh Addressing header to support sub-IP forwarding, a Fragmentation header
to support the IPv6 minimum MTU requirement [RFC2460], and stateless header
compression for IPv6 datagrams (LOWPAN_HC1 and LOWPAN_HC2) to reduce the
relatively large IPv6 and UDP headers down to (in the best case) several bytes.
In September 2011 the standard update was published - [RFC6282]. .. c:function:: int ed(struct ieee802154_hw *hw, u8 *level):
It deprecates HC1 and HC2 compression and defines IPHC encoding format which is
used in this Linux implementation.
All the code related to 6lowpan you may find in files: net/6lowpan/* Handler that 802.15.4 module calls for Energy Detection from the hardware
and net/ieee802154/6lowpan/* device.
To setup a 6LoWPAN interface you need: .. c:function:: int set_channel(struct ieee802154_hw *hw, u8 page, u8 channel):
1. Add IEEE802.15.4 interface and set channel and PAN ID;
2. Add 6lowpan interface by command like: Set radio for listening on specific channel of the hardware device.
# ip link add link wpan0 name lowpan0 type lowpan
3. Bring up 'lowpan0' interface Moreover IEEE 802.15.4 device operations structure should be filled.
...@@ -25,6 +25,7 @@ Contents: ...@@ -25,6 +25,7 @@ Contents:
device_drivers/intel/iavf device_drivers/intel/iavf
device_drivers/intel/ice device_drivers/intel/ice
devlink-info-versions devlink-info-versions
ieee802154
kapi kapi
z8530book z8530book
msg_zerocopy msg_zerocopy
......
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